I know there is a men's group called CNclub. I don't know if it is what you are looking for. The lead singer is Jung Yong Hwa, who plays the girl Xu Xian in We Are Married. Together, they are called "Sweet Potato Couples" and are very popular in Korea. In addition, their better song is Lonely Man. I don't know why you said it was 4club. In fact, there is a Korean women's group called 4minute, but I'm not very familiar with this group. Baidu Encyclopedia has a brief introduction about 4minute, you can have a look, but there seems to be no CNclub. I hope what I said can help you.